The present invention relates to an internal locking arrangement for a switch machine.
There is already known an internal locking arrangement for a switch machine wherein the throwing forces act on the switch points via a sliding piece disposed in the mechanism casing and movable in the direction of movement of the switch points, and via two rods, and wherein the driving force is transmitted from the drive unit to the sliding piece via a spring box lockable in its limit positions and containing a spring-loaded roller or ball which releasably engages in a corresponding depression in the sliding piece.
An internal locking arrangement of this type forms part of a switch machine with internal locking as disclosed in published German application DE-OS No. 26 06 664.
In that switch machine, locking is effected via so-called detector bars (locking bars), which are actually designed to detect the limit positions of the switch and actuate contacts in response thereto. Detector bars which are to be used as locking elements must be much more rugged in construction and, hence, larger in dimensions than would be necessary to perform a pure detecting function. Trailable and non-trailable designs of switch machines lockable via detector bars differ in various respects and include different parts and, except in the embodiment described in claim 4 of the above-identified German application, subsequent conversion of the switch machine (e.g. from trailable to non-trailable) necessitates replacing many parts of the machine.